Modification of the Kaolinite Hydroxyl Surfaces through Intercalation with Potassium Acetate under Pressure.

Kaolinite hydroxyl surfaces have been modified upon intercalation with potassium acetate under a range of conditions. Modification is observed by changes in the hydroxyl stretching region using Raman and infrared spectroscopy. Upon the intercalation of low defect kaolinite with potassium acetate under a pressure of 20 bars and 220 degreesC, the Raman spectra showed additional bands at 3590, 3603, and 3609 cm-1. The DRIFT spectra of this intercalate showed new bands at 3595 and 3605 cm-1. These bands are attributed to the inner surface hydroxyls hydrogen bonded to the acetate anion. Intercalation under 20 bars pressure at 220 degreesC caused the differentiation of the inner surface hydroxyl groups, resulting in these additional bands. By using milder conditions of 2 bars and at 120 degreesC, additional Raman bands were found at 3592, 3600, and 3606 cm-1. If the kaolinite was intercalated at 1 bar and 100 degreesC, a new broad Raman band was found at 3605 cm-1. It is proposed that the effect of intercalation of the low defect kaolinite under pressure caused the kaolinite to become disordered and this disordering was dependent upon the temperature of intercalation. Copyright 1998 Academic Press.